The invention relates to an electron tube device comprising an electron tube having at least one line cathode, and an electric power source for the supply of power pulses to the line cathode.
Such an electron tube device is known from U.S. Pat. No. 4,167,690, in which a description is given of a display device having a line cathode which is heated by means of power pulses. Between each consecutive pair of pulses there is an interval. During this interval an electron flow is extracted from the line cathode. This electron flow is modulated by a modulation system and an image is displayed on a display screen.
It has been found that after such an electron tube device is switched on, relatively rapidly varying initial changes occur during the transient time in the number of electrons emitted per unit of time by the line cathode. Also during the life cycle of the electron tube device slowly varying temporal changes occur in the number of electrons emitted. In a display device these changes reveal themselves as changes in the intensity of the image displayed, which is undesired.